The head of the troubled National Museum of Ireland (NMI) has warned staff not to speak to the media without first obtaining his approval.

The instruction was issued by the museum's outgoing director Raghnall Ó Floinn just a fortnight after a former employee spoke out about her experience of being sexually harassed while working there.

Archaeologist Adrienne Corless severely criticised the museum, saying it badly mishandled matters and failed to take proper action against her harasser.

But the museum had denied the issuing of the circular was linked to an interview with Ms Corless published in the Irish Independent on November 11 last or other articles which subsequently appeared in other news outlets.

In a circular on November 27, Mr Ó Floinn also warned staff they were subject to the provisions of the Officials Secrets Act.

Ms Corless, who worked at the museum between 2004 and 2012, said she was "shocked" and "furious" when she heard of the circular.

She said she believed it was "completely out of order" and would have a chilling effect on staff speaking out about problems at the museum.

The institution has been dogged by controversy in recent years, with a number of staff voicing concerns over alleged harassment and bullying.

In the circular, Mr Ó Floinn said staff members "should not make any written or verbal communication with representatives of the media nor address any group on matters pertaining to their work or the operations of the National Museum" without first obtaining his approval.

He also told staff they should note that, subject to the Official Secrets Act and the Freedom of Information Act, they were "prohibited from disclosing to third parties any confidential information that is connected with the performance of their duties relating to the museum", either during or subsequent to their period of employment, without his written consent.

The NMI said measures are being taken to address issues raised by staff and improve the working environment in the museum, which operates at three sites in Dublin and one in Co Mayo.

However, Ms Corless said the circular would only serve to discourage employees from speaking out. "In my time there we would have all felt quite helpless. It really was frowned upon for anyone to question anything in there," she said.

Although an investigation found she had been repeatedly sexually harassed by the colleague, he only received a minor reprimand and was allowed to keep his job. He was eventually suspended by the museum last year, but has issued High Court proceedings in a bid to be reinstated.

In a statement, the NMI said the "reminder to staff in respect of confidentiality" was "in no way" linked to Ms Corless's interview in November or other media coverage and the timing of the circular to staff was an "operational matter".